This invention relates to one-way clutches, and more particularly to an improved roller type, one-way clutch and to a backstop incorporating such a clutch.
Clutches are well known which are free-wheeling in one direction of relative rotation between their elements and which will automatically prevent reverse rotation. One form of such one-way clutches employs a series of rollers which are disposed between inner and outer races. One of the races has a smooth cylindrical surface and the other is provided with a series of indentations formed by inclined surfaces which define wedge-shaped spaces between the races. In one direction of rotation of the races relative to each other, the rollers will seek the wide portion of the wedge-like space and thus not impede the relative rotation of the races. Attempts to rotate the races relative to each other in an opposite direction will, however, result in the rollers being wedged between the races and thereby preventing rotation.
In such roller type, one-way clutches it is common to employ a light tension spring to urge the rollers into an engaging, or wedging position so that as soon as rotation in the locked direction is attempted, the rollers will be positively engaged to halt the rotation. It is also common to employ a mechanism to prevent the rollers from being moved relatively too far into the deepest portion of the indentations. Thus, as shown in U.S. Pat. No. 3,017,002 issued Jan. 16, 1962 to J. A. Marland for "One-Way Clutch", a stop lug is connected to the cage for the rollers and is adapted to engage a portion of one of the indentations so as to prevent the rollers held by the cage from themselves shifting to the deepest part of the indentations. In such patent, the stop lugs ride in special slots cut in the inner race for that purpose and thereby also act to provide axial restraint of the cage assembly relative to the inner race.
One-way clutches are often employed in backstops whose function it is to prevent a shaft from being rotated in a reverse direction so that a prime mover, for example, driving the shaft will not be damaged by the reverse rotation. Conveyor drive trains are one type of installation in which backstops are typically employed. In a backstop the inner race is normally connected to the shaft to be controlled and the outer race is commonly connected to a stationary support. The connection to the stationary support may be by means of a torque arm which engages an abutment if reverse rotation is attempted. In such instances, the outer race is essentially held stationary except for the very slight motion which is permitted before the torque arm engages the abutment.
Examples of backstops employing a roller type, one-way clutch are found in U.S. Pat. No. 2,865,474 issued Dec. 23, 1958 to J. A. Marland for "One-Way Automatic Backstops", and in U.S. Pat. No. 3,236,337 issued Feb. 22, 1966 to J. A. Marland and C. W. Hill for "One-Way Backstop".